Abstract: Disclosed is a device for providing illumination on a helicoptor rotor blade. A chemiluminescent light source, including a translucent container and a chemiluminescent substance received therein, is attached to the outer end of a helicoptor rotor blade so that the helicoptor operator, or a remote observer, may be provided with a light marker indicating the outer circumference of the blade's rotational path.

Abstract: Visually observable safe limits for the proximity of an aircraft, such as a helicopter, to obstructions are provided by pairs of lights which provide collimated beams intersecting at limit points located radially outwardly of the arc of the helicopter rotor blades so that light scattered from the intersecting beams at the limit points provides the helicopter pilot with visual references of the rotor arc. Each light of each pair has a concave reflector and a lamp at the focal point of the reflector to provide the collimated beams and transparent plastic shields over the open ends of the reflectors have concavities in central portions to provide diverging beams that illuminate the obstructions.

Abstract: A measuring device (1, 12, 13, 14) is equipped with a blade angle indicator (1) indicating the blade angle adjustment of the rotor blades of a helicopter, a pressure altimeter (13) and an outside temperature probe (14). The measuring device (1, 12, 13, 14) is linked to a control device (4-6) which has a central processing unit (4) and a program memory (5). The memory (5) stores data processing instructions for determining density height from pressure height and outside temperature as well as data processing instructions corresponding to the helicopter operating instructions for determining the permissible maximum value of the blade angle from the density height. The control device (4-6) periodically determines the density height on the basis of the prevailing pressure height and outside temperature and the corresponding permissible maximum value of the blade angle.

Abstract: A visual alarm suitable for use with night vision goggles comprises a red incandescent lamp (105); a blue, green or blue-green electroluminscent panel (130); and control means to sequentially activate the above-mentioned light sources. Brief activation of the red lamp causes momentary partial blooming of the night vision goggles to warn of an emergency condition. Subsequent steady energization of the electroluminescent panel provides a continuous observable alarm which does not interfere with operation of the night vision goggles.

Abstract: A warning system for rotary wing aircraft compares the accumulated altitude loss after take-off of the aircraft with its altitude above ground, and generates a warning if the altitude loss is excessive for the altitude above ground at which the aircraft is flying. The position of the landing gear, the speed of the aircraft and its altitude enable the system only during the take-off and missed approach phases of operation in order to minimize nuisance warnings during other phases. The relationship between radio altitude and altitude loss required to generate a warning is optimized for rotary wing aircaft such as helicopters.

Abstract: A system for warning the pilot of a rotary wing aircraft such as a helicopter of a flight condition that, if left uncorrected, would result in the tail of the aircraft striking the ground monitors the altitude above ground, descent rate, pitch and pitch rate of the aircraft and provides a warning if the relationship between the aforementioned parameters is such that a tail strike is imminent.

Abstract: A warning device, for a helicopter with a tail rotor and a mechanical protection device therefor, for giving during emergency power-loss landings a flare signal to the pilot to initiate flare followed by a tail/ground contact warning signal when the helicopter tail approaches too closely the ground. The warning device comprises in one embodiment a height-finder with two switchable transmitting/receiving antennas mounted at the helicopter tail to produce respectively, when switched into use, a height-finding beam backwards and obliquely downwards or forwards and obliquely downwards. Height signals obtained initially using antenna 40 are processed by computing means and initiate at a predetermined initial flare altitude a flare warning signal whereafter height signals from antenna 26 are used to determine the sink rate of the tail and in dependence upon this sink rate and the instantaneous height, a warning signal is initiated if this corresponds to a predetermined relative relationship.

Abstract: A warning system for providing an aural warning to the pilot of a rotary wing aircraft monitors the altitude above ground and barometric descent rate of the aircraft and generates the warning if the descent rate of the aircraft is excessive for the altitude at which the aircraft is flying. The system provides two distinct warnings, one being an early warning advising the pilot of a hazardous condition, and the other being a warning alerting the pilot of imminent danger. The system also includes tactical and non-tactical modes of operation, wherein the warning criteria are adjusted to meet tactical and non-tactical flight conditions.

Abstract: A warning device, for a helicopter with a tail rotor and a mechanical protection device (15) therefor, for giving warning if the helicopter tail approaches too closely the ground or an obstruction. The warning device comprises a height-finder (11) with a transmitting/receiving antenna (26) mounted at the helicopter tail to produce a height-finding beam backwards and obliquely downwards. Height signals are processed by computing means (12) to determine the sink rate of the tail and in dependence upon this sink rate and the instantaneous height, a warning signal is initiated if this corresponds to a predetermined relative relationship. The higher the sink rate the greater is the height at which the warning signal is initiated and vice versa.In the preferred arrangement the beam is directed substantially along or parallel to the axis of the mechanical protection device (15).